Latch Mechanism for Surgical Instruments

ABSTRACT

A surgical instrument includes a pair of jaw members moveable between a spaced-apart and an approximated position. A drive bar is translatable between a distal and a proximal position for moving the jaw members between the spaced-apart and approximated positions. A lever is moveable between an initial position and an actuated position for translating the drive bar between the distal and proximal positions. A sleeve disposed about the drive bar includes an annular track having a substantially radial segment(s) and a substantially longitudinal segment(s). A collar interdisposed between the sleeve and the drive bar includes a stop member(s) extending radially outwardly therefrom. The stop member(s) is engaged within the track and is translatable from a first position, wherein the stop member is positioned within the longitudinal segment, to a second position, wherein the stop member is engaged within the radial segment, to lock the lever in the actuated position.

BACKGROUND

The present disclosure relates to surgical instruments. Moreparticularly, the present disclosure relates to releasable latchmechanisms for use with surgical instruments.

TECHNICAL FIELD

Electrosurgical instruments, e.g., forceps, utilize both mechanicalclamping action and electrical energy to effect hemostasis by heatingtissue and blood vessels to coagulate, cauterize and/or seal tissue. Asan alternative to open forceps for use with open surgical procedures,many modern surgeons use endoscopic or laparoscopic instruments forremotely accessing organs through smaller, puncture-like incisions ornatural orifices. As a direct result thereof, patients tend to benefitfrom less scarring and reduced healing time.

Many endoscopic surgical procedures require cutting or ligating bloodvessels or vascular tissue. Due to the inherent spatial considerationsof the surgical cavity, surgeons often have difficulty suturing vesselsor performing other traditional methods of controlling bleeding, e.g.,clamping and/or tying-off transected blood vessels. By utilizing anendoscopic electrosurgical forceps, a surgeon can either cauterize,coagulate/desiccate and/or simply reduce or slow bleeding simply bycontrolling the intensity, frequency and duration of the electrosurgicalenergy applied through the jaw members to the tissue. Most small bloodvessels, i.e., in the range below two millimeters in diameter, can oftenbe closed using standard electrosurgical instruments and techniques.However, if a larger vessel is ligated, it may be necessary for thesurgeon to convert the endoscopic procedure into an open-surgicalprocedure and thereby abandon the benefits of endoscopic surgery.Alternatively, the surgeon can seal the larger vessel or tissue.Typically, after a vessel or tissue is sealed, the surgeon advances aknife to sever the sealed tissue disposed between the opposing jawmembers.

SUMMARY

The present disclosure relates to a surgical instrument including an endeffector assembly having a pair of jaw members pivotably coupled to oneanother. One or both of the jaw members is moveable relative to theother between a spaced-apart position and an approximated position forgrasping tissue therebetween. A drive bar defining a longitudinal axisis longitudinally translatable between a distal position and a proximalposition for moving the jaw members between the spaced-apart positionand the approximated position. A latch mechanism is also provided. Thelatch mechanism includes a lever that is moveable between an initialposition and an actuated position for translating the drive bar betweenthe distal position and the proximal position and, thus, for moving thejaw members between the spaced-apart position and the approximatedposition. A sleeve is co-axially disposed about the drive bar. Thesleeve includes a track extending annularly therearound. Morespecifically, the track includes one or more substantially radialsegments and one or more substantially longitudinal segments. Arotatable collar is interdisposed between the sleeve and the drive bar.The rotatable collar includes one or more stop members extendingradially outwardly from an outer periphery thereof. The stop member(s)is engaged within the track and is configured to translate along thetrack from a first position, corresponding to the initial position ofthe lever, wherein the stop member(s) is positioned within one of thesubstantially longitudinal segments, to a second position, correspondingto the actuated position of the lever, wherein the stop member(s) isengaged within one of the substantially radial segments to lock thelever in the actuated position.

In one embodiment, the stop member(s) are configured to translate fromthe first position to a third position, corresponding to anover-actuated position, and back to the second position such that thestop member(s) is translated along the track from one of thesubstantially longitudinal segments to one of the substantially radialsegments to lock the lever in the actuated position. Similarly, uponmovement of the lever from the actuated position to the over-actuatedposition, e.g., upon movement of the stop member(s) from the secondposition to the third position, the stop member(s) is translated alongthe track from the substantially radial segment to one of thesubstantially longitudinal segments to unlock the lever from theactuated position.

In another embodiment, the track includes a plurality of alternatingsubstantially longitudinal segments and substantially radial segmentsdisposed annularly about the sleeve. The substantially longitudinalsegments may be configured to extend distally along the sleeve relativeto the substantially radial segments.

In yet another embodiment, a biasing member is annularly disposedbetween the drive bar and the sleeve. The biasing member is configuredto bias the rotatable collar distally relative to the sleeve.

Another embodiment of a surgical instrument in accordance with thepresent disclosure includes an end effector assembly, a drive bar and alatch mechanism. The end effector assembly includes a pair of jawmembers pivotably coupled to one another. One or both of the jaw membersare moveable relative to the other between a spaced-apart position andan approximated position for grasping tissue therebetween. The drive bardefines a longitudinal axis and is longitudinally translatable between adistal position and a proximal position for moving the jaw membersbetween the spaced-apart position and the approximated position. Thelatch mechanism includes a lever that is moveable between an initialposition and an actuated position for translating the drive bar betweenthe distal position and the proximal position and, thus, for moving thejaw members between the spaced-apart and approximated positions. Thelatch mechanism further includes a cartridge including first and secondlumens defined therein and extending longitudinally therethrough insubstantially parallel orientation relative to one another. The firstlumen is configured to slidably receive a portion of the drive bartherethrough. A rotatable post including a fixed end and a free end isslidably disposed within the second lumen of the cartridge and includesa track extending annularly therearound toward the free end thereof. Thetrack includes one or more substantially radial segments and one or moresubstantially longitudinal segments. One or more stop members arefixedly coupled to the cartridge. More specifically, the stop member(s)extends radially inwardly into the second lumen of the cartridge toengage the track. The stop member(s) is configured to translate alongthe track from a first position, corresponding to the initial positionof the lever, wherein the stop member(s) is positioned within one of thesubstantially longitudinal segments, to a second position, correspondingto the actuated position of the lever, wherein the stop member(s) isengaged within one of the substantially radial segments to lock thelever in the actuated position.

In one embodiment, the stop member(s) are configured to translate fromthe first position to a third position, corresponding to anover-actuated position, and back to the second position such that thestop member(s) is translated along the track from one of thesubstantially longitudinal segments to one of the substantially radialsegments to lock the lever in the actuated position. Similarly, uponmovement of the lever from the actuated position to the over-actuatedposition, e.g., upon movement of the stop member(s) from the secondposition to the third position, the stop member(s) is translated alongthe track from the substantially radial segment to one of thesubstantially longitudinal segments to unlock the lever from theactuated position.

In another embodiment, a biasing member is annularly disposed betweenthe drive bar and the cartridge. The biasing member is configured tobias the cartridge distally relative to the rotatable post.

Still another embodiment of a surgical instrument in accordance with thepresent disclosure includes an end effector assembly, a drive bar, and alatch mechanism. The end effector assembly includes a pair of jawmembers pivotably coupled to one another. One (or both) of the jawmembers is moveable relative to the other between a spaced-apartposition and an approximated position for grasping tissue therebetween.The drive bar, as in the previous embodiments, is longitudinallytranslatable between a distal position and a proximal position formoving the jaw members between the spaced-apart position and theapproximated position and a lever of the latch mechanism, in turn, ismoveable between an initial position and an actuated position fortranslating the drive bar from the distal position to the proximalposition. The latch mechanism further includes a post having a fixed endand a free end. The post is pivotable about the fixed end thereof. Asleeve is rotatably and slidably disposed about the post and includes atrack defined therein and extending annularly therearound. The trackincludes one or more substantially radial segments and one or moresubstantially longitudinal segments. One or more stop members is engagedwithin the track, the stop member(s) configured to translate along thetrack from a first position, corresponding to the initial position ofthe lever, wherein the stop member(s) is positioned within one of thesubstantially longitudinal segments, to a second position, correspondingto the actuated position of the lever, wherein the stop member(s) isengaged within one of the substantially radial segments to lock thelever in the actuated position.

As in the previous embodiment, the stop member(s) may be configured totranslate from the first position to a third position, corresponding toan over-actuated position, and back to the second position such that thestop member(s) is translated along the track from one of thesubstantially longitudinal segments to one of the substantially radialsegments to lock the lever in the actuated position. Similarly, uponmovement of the lever from the actuated position to the over-actuatedposition, e.g., upon movement of the stop member(s) from the secondposition to the third position, the stop member(s) is translated alongthe track from the substantially radial segment to one of thesubstantially longitudinal segments to unlock the lever from theactuated position.

In one embodiment, the lever includes a pair of flanges disposed oneither side of the sleeve. Each flange includes a stop members extendinginwardly therefrom, e.g., toward the sleeve, such that movement of thelever effects corresponding movement of the stop members along thetrack.

In another embodiment, a biasing member is disposed between the sleeveand the free end of the post. The biasing member is configured to biasthe sleeve distally relative to the post.

In yet another embodiment, an interference member is disposed at thefree end of the post. The interference member is configured such that,upon movement of the lever to the actuated position, the interferencemember is pivoted into engagement with the drive bar to inhibit thedrive bar from returning distally, i.e., to retain the drive bar in theproximal position.

In still another embodiment, the latch mechanism further includes an“L”-spring. The “L”-spring includes a first end that is rotatablycoupled to the post toward the fixed end of the post, and a second endthat has the stop member extending therefrom.

In still yet another embodiment, the lever includes a pair of flangesdisposed on either side of the post and coupled between the sleeve andthe free end of the post such that movement of the lever effectscorresponding movement of the sleeve relative to the stop member, e.g.,the “L”-spring, thereby moving the stop member along the track.

Similar to previous embodiments, the track may include a plurality ofalternating substantially longitudinal segments and substantially radialsegments disposed about the sleeve.

In another embodiment, the track includes a contoured floor to define athree-dimensional track. More specifically, the contoured floor isconfigured such that the stop member(s) is moved three-dimensionallyrelative to the track as the stop member(s) is moved along the trackbetween the substantially longitudinal segments and the substantiallyradial segments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the presently disclosed latch mechanisms aredescribed herein with reference to the drawings, wherein:

FIG. 1A is a perspective view of a forceps including an end effectorassembly in accordance with an embodiment of the present disclosurewherein the jaw members of the end effector assembly are disposed in aspaced-apart position;

FIG. 1B is a perspective view of the forceps of FIG. 1A wherein the jawmembers of the end effector assembly are disposed in an approximatedposition;

FIG. 2A is a side, cross-sectional view of the forceps of FIG. 1A,including a latching mechanism having a lever disposed in an initialposition;

FIG. 2B is a schematic illustration of the latch mechanism of FIG. 2Ashown in the unlatched condition;

FIG. 3 is an enlarged, top view of a rotatable collar of the latchmechanism of FIG. 2A;

FIG. 4A is a side, cross-sectional view of the latch mechanism of FIG.2A, wherein the lever is disposed in an actuated position;

FIG. 4B is a schematic illustration of the latch mechanism of FIG. 2Ashown transitioning between the unlatched condition and the latchedcondition;

FIG. 5A is a side, cross-sectional view of the latch mechanism of FIG.2A wherein the lever has been moved to the actuated position and hasthereafter been released;

FIG. 5B is a schematic illustration of the latch mechanism of FIG. 2Ashown disposed in the latched condition;

FIG. 6A is a side, cross-sectional view of the latch mechanism of FIG.2A, wherein the lever has been moved from the actuated position to aposition proximal of the actuated position;

FIG. 6B is a schematic illustration of the latch mechanism of FIG. 2Ashown transitioning from the latched condition back to the unlatchedcondition;

FIG. 7 is a schematic illustration showing the latch mechanism of FIG.2A transitioning from the unlatched condition to the latched conditionand back to the unlatched condition;

FIG. 8 is a side, cut-away view of an other embodiment of a latchmechanism configured for use with the forceps of FIG. 1A, wherein thelever is disposed in an initial position;

FIG. 9 is a side, cut-away view of the latch mechanism of FIG. 8,wherein the lever has been moved to the actuated position;

FIG. 10 is a side, cut-away view of the latch mechanism of FIG. 8,wherein the latch mechanism is disposed in the latched condition,retaining the lever in the actuated position;

FIG. 11 is a side, cut-away view of the forceps of FIG. 8, wherein thelever has been moved from the actuated position to a position proximalof the actuated position to unlatch the latch mechanism;

FIG. 12 is a side, cross-sectional view of yet another embodiment of alatch mechanism configured for use with the forceps of FIG. 1A, whereinthe lever is disposed in an initial position;

FIG. 13 is a side, cross-sectional view of the forceps of FIG. 12,wherein the lever is disposed in the actuated position and wherein thelatch mechanism is disposed in the latched condition;

FIG. 14 is a side view of the post assembly of the latch mechanism ofthe forceps of FIG. 12 shown with parts separated;

FIG. 15 is a front view of the lever of the latch assembly of FIG. 12;

FIG. 16 is a side, cross-sectional view of still another embodiment of alatch mechanism configured for use with the forceps of FIG. 1A, whereinthe latch mechanism is disposed in an unlatched condition;

FIG. 17 is a side, cross-sectional view of the latch mechanism of FIG.16, wherein the latch mechanism is disposed in a latched condition;

FIG. 18 is a side, cross-sectional view of still yet another embodimentof a latch mechanism configured for use with the forceps of FIG. 1A,wherein the latch mechanism is disposed in an unlatched condition;

FIG. 19 is a side, cross-sectional view of the latch mechanism of FIG.18, wherein the latch mechanism is disposed in a latched condition;

FIG. 20A is a greatly-enlarged, side view of the latch mechanism of FIG.18; and

FIG. 20B is a transverse-cross sectional view of the latch mechanism ofFIG. 20A represented linearly.

DETAILED DESCRIPTION

Embodiments of the present disclosure are described in detail withreference to the drawing figures wherein like reference numeralsidentify similar or identical elements. As used herein, the term“distal” refers to the portion that is being described which is furtherfrom a user, while the term “proximal” refers to the portion that isbeing described which is closer to a user.

Turning now to FIGS. 1A and 1B, forceps 10 is one example of aninstrument for use in accordance with the present disclosure. Forceps 10including a housing 20, a handle assembly 30, a lever latch assembly 40,a trigger assembly 80, a rotating assembly 85, and an end effectorassembly 100. Forceps 10 further includes a shaft 12 having a distal end14 configured to mechanically engage end effector assembly 100 and aproximal end 16 that mechanically engages housing 20. Alternatively, anysurgical instrument having a lever operable to control one or morefunctions of the end effector assembly may be used in accordance withthe present disclosure.

With continued reference to FIGS. 1A and 1B, end effector assembly 100includes a pair of opposing jaw members 110 and 120. End effectorassembly 100 is designed as a unilateral assembly, i.e., jaw member 120is fixed relative to the shaft 12 and jaw member 110 is moveable about apivot 103 relative to jaw member 120. However, either, or both of jawmembers 110, 120 may be moveable with respect to the other. In eitherembodiment, jaw members 110, 120 are moveable from a spaced-apartposition, as shown in FIG. 1A, to an approximated position, as shown inFIG. 1B, to grasp tissue therebetween. Further, one or both of jawmembers 110, 120 may include an electrically conductive tissue sealingsurface 112, 122, respectively. Sealing surfaces 112, 122 are disposedin opposed relation relative to one another such that, with jaw members110, 120 in the approximated position grasping tissue therebetween,electrosurgical energy may be supplied to one or both of sealingsurfaces 112, 122 of jaw members 110, 120, respectively, to seal tissuegrasped therebetween.

One or both of jaw members 110, 120 may also include a longitudinallyextending blade channel 130 to permit reciprocation of a blade (notshown) therethrough for dividing tissue grasped therebetween. Triggerassembly 80 is operably coupled to the blade (not shown) such that, uponactuation of trigger 82, the blade (not shown) is translated from aretracted position to an extended position wherein the blade (not shown)is advanced between jaw members 110, 120 to cut tissue graspedtherebetween. Further, trigger 82 may be biased toward an un-actuatedposition such that, upon release of trigger 82, the blade (not shown) isreturned to the retracted position. A blade-lock feature may also beprovided to inhibit translation of the blade to the extended positionwhen jaw members 110, 120 are in the spaced-apart position.

Rotating assembly 85 is integrally associated with housing 20 and isrotatable in either direction about a longitudinal axis “X-X” to rotatejaw members 110, 120 with respect to housing 20 about longitudinal axis“X-X,” allowing jaw members 110, 120 to be repositioned relative totissue to be grasped, sealed and/or divided.

Handle assembly 30 extends downwardly from housing 20 and is releasablyengageable with housing 20. Handle assembly 30 is ergonomicallyconfigured such that, when engaged with housing 20, a surgeon may grasphandle assembly 30 and operate lever latch assembly 40, trigger assembly80 and/or rotating assembly 85 with a single hand. Handle assembly 30may further includes a battery pack (not shown) disposed within abattery housing 32. The battery pack (not shown) of handle assembly 30provides power to forceps 10, e.g., for energizing sealing surfaces 112,122 of jaw members 110, 120, respectively. More particularly, thebattery pack (not shown) may be configured to electrically couple to agenerator (not shown) disposed within housing 20 for powering thegenerator (not shown). The generator (not shown), in turn, supplies thedesired energy to sealing surfaces 112, 122 of jaw members 110, 120,respectively, of end effector assembly 100. Alternatively, forceps 10may be configured to connect to an external energy source (not shown),e.g., via an electrosurgical cable (not shown), obviating the need forthe battery pack (not shown) and generator (not shown) to be disposedwithin handle assembly 30 and housing 20, respectively.

With continued reference to FIGS. 1A and 1B, battery housing 32 ofhandle assembly 30 may include mechanical keying features (not shown)configured complementarily to mechanical keying features associated withhousing 20 such that handle assembly 30 may be securely locked inmechanical engagement with housing 20. Upon such engagement, the batterypack (not shown) is electrically coupled to the generator (not shown).The battery housing 32 may also be released from housing 20, e.g., toreplace or recharge the battery pack (not shown).

Continuing with reference to FIGS. 1A and 1B, lever latch assembly 40includes a lever 41 pivotably coupled to housing 20 and extendingdownwardly therefrom. Lever 41 is ultimately connected to a driveassembly that, as will be described in greater detail below, togethermechanically cooperate to impart movement of jaw members 110 and 120between the spaced-apart position (FIG. 1A) and the approximatedposition (FIG. 1B). More particularly, lever 41 is selectively moveablefrom an initial position (FIG. 1A), wherein lever 41 is spaced-apartfrom handle assembly 30, to an actuated position (FIG. 1B), whereinlever 41 is positioned adjacent handle assembly 30, to move jaw members110, 120 from the spaced-apart position (FIG. 1A) to the approximatedposition (FIG. 1B). Lever latch assembly 40 is configured to permitmovement of lever 41 between the initial position and the actuatedposition and for releasably locking lever 41 in the actuated position.In other words, lever latch assembly 40 is configured to selectivelymove jaw members 110, 120 between the spaced-apart position and theapproximated position and to releasably lock jaw members 110, 120 in theapproximated position. Further, lever 41 may be biased toward theinitial position, such that jaw members 110, 120 are biased toward thespaced-apart position. Various embodiments of lever latching assembliesconfigured for use with forceps 10 (or other suitable surgicalinstruments (not shown)) will be described below with reference to FIGS.2A-20B.

With reference now to FIGS. 2A-7, and initially to FIG. 2A, oneembodiment of a lever latch assembly in accordance with the presentdisclosure, lever latch assembly 140, is shown. Lever latch assembly 140includes a lever 141 that is pivotably coupled to housing 20 and extendsdownwardly therefrom. More specifically, lever 141 includes a graspingportion 142 that extends downwardly from housing 20, and first andsecond flanges 143 that extend upwardly from grasping portion 142 intohousing 20. Flanges 143 extend upwardly on either side of drive bar 191,ultimately engaging pivot pin 145 on either end thereof, thus allowinglever 141 to pivot about pivot pin 145 relative to housing 20.

Continuing with reference to FIG. 2A, drive bar 191 is disposed aboutlongitudinal axis “X-X” and extend distally through housing 20 and shaft12, ultimately coupling to jaw member 110 (and/or jaw member 120) of endeffector assembly 100. More specifically, drive bar 191 is pivotablyengaged to jaw member 110 at a position offset relative to pivot pin 103such that proximal translation of drive bar 191 pulls jaw member 110 torotate in a first direction about pivot pin 103 relative to jaw member120, e.g., from the spaced-apart position (FIG. 1A) to the approximatedposition (FIG. 1B) and such that distal translation of drive bar 191pushes jaw member 110 to rotate about pivot pin 103 in the oppositedirection, e.g., from the approximated position to the spaced-apartposition. The reverse configuration, e.g., wherein distal translation ofdrive bar 191 effects closure of jaw members 110, 120 and where proximaltranslation of drive bar 191 opens jaw members 110, 120 and othersuitable drive mechanisms (not shown) are also contemplated.

As shown in FIG. 2A, a mandrel 192 is disposed about drive bar 191toward a proximal end thereof and includes proximal and distal rims 193,194, respectively, Mandrel 192 is fixedly engaged to drive bar 191 andis annularly disposed between drive bar 191 and flanges 143 of lever141. Proximal and distal rims 193, 194, respectively, of mandrel 192extend radially outwardly therefrom to retain flanges 143 of lever 141therebetween. Accordingly, as lever 141 is moved proximally, e.g., aslever 141 is pivoted about pivot pin 145 from the initial position tothe actuated position, flanges 143 contact proximal rim 193 of mandrel192 and urge drive bar 191 proximally. On the other hand, as lever 141is moved distally, e.g., as lever 141 is returned to the initialposition, flanges 143 contact distal rim 194 of mandrel 192 and urgedrive bar 191 distally. Put more generally, mandrel 192 couples flanges143 of lever 141 to drive bar 191 such that jaw members 110, 120 aremoved from the spaced-apart position (FIG. 1A) to the approximatedposition (FIG. 1B) as lever 141 is moved from the initial position tothe actuated position and such that jaw members 110, 120 are moved fromthe approximated position (FIG. 1B) back to the spaced-apart position(FIG. 1A) as lever 141 is returned from the actuated position back tothe initial position.

With reference now to FIGS. 2A-3, housing 20 of forceps 10 includes anouter sleeve 150 disposed therein and fixedly engaged thereto and aninner sleeve 151 disposed within outer sleeve 150 and engaged to drivebar 191. Outer and inner sleeves 150, 151, respectively, are centeredabout longitudinal axis “X-X.” inner sleeve 151, drive bar 191, andmandrel 192 are slidably disposed within outer sleeve 150 such thatproximal and distal rims 193, 194, respectively, of mandrel 192 protruderadially outwardly from the open lateral sides of inner sleeve 151,allowing flanges 143 of lever 141 to engage mandrel 192 and, thus, drivebar 191, externally of outer sleeve 150. Further, a biasing member,e.g., spring 154, is disposed between proximal wall 152 of inner sleeve151 and proximal flange 193 of mandrel 192 to bias drive bar 191 towarda distal position, e.g., to bias jaw members 110, 120 toward aspaced-apart position. As can be appreciated, as lever 141 is moved fromthe initial position to the actuated position, mandrel 192 and drive bar191 are translated proximally relative to outer and inner sleeves 150,151, respectively, against the bias of spring 154 to move jaw members110, 120 from the spaced-apart position to the approximated position.Likewise, when lever 141 is released, mandrel 192 and drive bar 191 aretranslated distally relative to outer and inner sleeves 150, 151,respectively, under the bias of spring 154, to return jaw members 110,120 to the spaced-apart position.

Continuing with reference to FIGS. 2A-3, mandrel 192 further includes adistal extension 155 extending distally therefrom. Distal extension 155of mandrel 192 is configured to retain a rotatable collar 156 therein.Rotatable collar 156 is longitudinally fixed relative to mandrel 192 anddrive bar 191 but is permitted to rotate about longitudinal axis “X-X”relative to mandrel 192 and drive bar 191. As best shown in FIG. 3,rotatable collar 156 includes a pair of diametrically-opposed stopmembers 158 extending radially outwardly from an outer peripherythereof. Although two stop members 158 are shown, greater or fewer thantwo stop members 158 may also be provided.

Stop members 158, as mentioned above, extend radially outwardly fromrotatable collar 156 to engage track 160 defined within outer sleeve150. More specifically, proximal portion 159 of outer sleeve 150includes a track 160 extending annularly therearound and configured toretain stop members 158 therein. As will be described in greater detailbelow, once lever 141 is moved from the initial position past theactuated position, e.g., to the over-actuated position, stop members 158of rotatable collar 156 are translated along and rotated relative totrack 160 of proximal portion 159 of outer sleeve 150. Thereafter, lever141 may be released such that stop members 158 are engaged within track160 to latch lever 141 in the actuated position, releasably latching jawmembers 110, 120 in the approximated position. Upon further actuation oflever 141, followed by release of lever 141, stop members 158 ofrotatable collar 156 are further translated along and rotated relativeto track 160 of distal portion 159 of outer sleeve 150 to unlatch leverlatch assembly 140, allowing lever 141 to return to the initial positionand allowing jaw members 110, 120 to return to the spaced-apartposition.

Referring once again to FIGS. 2A-7, the use and operation of lever latchassembly 140 will be described. Initially, as shown in FIG. 2A, lever141 is disposed in the initial position, jaw members 110, 120 aredisposed in the spaced-apart position, and stop members 158 of rotatablecollar 156 are disposed at distal ends 163 of longitudinal segments 162of track 160 of outer sleeve 150 (FIGS. 2B and 7). In this position,forceps 10 may be manipulated and/or end effector assembly 100 may berotated to position jaw members 110, 120 such that tissue to be grasped,sealed and/or divided is disposed therebetween.

Once end effector assembly 100 is positioned as desired, e.g., withtissue disposed between jaw members 110, 120, jaw members 110, 120 maybe moved to the approximated position to grasp tissue. To move jawmembers 110, 120 to the approximated position, lever 141 is pulledproximally from the initial position toward the actuated position, asshown in FIG. 4A. As lever 141 is pulled toward the actuated position,mandrel 192, drive bar 191, and collar 156 are translated proximallyagainst the bias of spring 154, pulling jaw member 110 to rotate aboutpivot pin 103 relative to jaw member 120 toward the approximatedposition. At the same time, stop members 158 of rotatable collar 156 aretranslated proximally along longitudinal segment 162 of track 160 ofouter sleeve 150.

Lever 141 is moved further proximally past the actuated position suchthat mandrel 192, drive bar 191, and rotatable collar 156 are likewisetranslated further proximally to move jaw members 110, 120 into furtherapproximation with one another. More specifically, lever 141 is movedproximally past the actuated position until stop members 158 have beentranslated proximally completely through longitudinal segments 162 oftrack 160 and into abutment with proximal surface 165 of annular segment164 of track 160, as best shown in FIG. 4B and FIG. 7 (position 2). Thisposition corresponds to the over-actuated position, e.g., where lever141 has been moved proximally beyond the actuated position and isinhibited from being depressed further due to the engagement of stopmembers 158 within proximal surface 165 of track 160. Proximal surface165 of annular segment 164 of track 160 defines a triangle-wave-shapedconfiguration including a plurality of alternative peaks 166 and valleys167. Accordingly, when stop members 158 contact proximal surface 165 oftrack 160, due to the triangle-wave-shaped configuration of proximalsurface 165 of track 160, stop members 158 are urged along the angledproximal surface 165 from the peaks 166 of proximal surface 165 to thevalleys 167 thereof. In other words, upon movement of lever 141 to theover-actuated position, stop members 158 are urged into contact withproximal surface 165 track 160 and are translated annularly along track160 such that rotatable collar 156 is rotated about longitudinal axis“X-X” relative to outer sleeve 150. As can be appreciated, withrotatable collar 156 having been rotated about longitudinal axis “X-X”relative to outer sleeve 150, stop members 158 are no longerlongitudinally aligned with longitudinal segments 162 of track 160.

As shown in FIG. 5B, upon release of lever 141 from the over-actuatedposition, e.g., allowing spring 154 to urge lever 141 distally back tothe actuated position, stop members 158 are translated distally relativeto track 160. However, with stop members 158 no longer aligned withlongitudinal segments 162 of track 160, lever 141 is only permitted toreturn distally to the actuated position, wherein stop members 158contact distal surface 168 of track 160 inhibiting further distalmovement. More specifically, similar to proximal surface 165 of track160, distal surface 168 of track 160 defines a triangle-wave-shapedconfiguration. As a result, as stop members 158 are urged into contactwith distal surface 168 of track 160, rotatable collar 156 is rotatedabout longitudinal axis “X-X” such that stop members 158 are translatedfrom the peaks 169 of distal surface 168 of track 160 to the valleys 171thereof. Once rotated into position, stop members 158 are retained inthe valleys 171 of distal surface 168 of track 160 under the bias ofspring 154. The engagement of stop members 158 within valleys 171 ofdistal surface of track 160 (FIG. 7) inhibits stop members 158, lever141, and drive bar 191 from returning distally. This positioncorresponds to the actuated position of lever 141 and the approximatedposition of jaw members 110, 120. In other words, the engagement of stopmembers 158 within distal surface 168 of track 160 latches jaw members110, 120 in the approximated position.

With jaw members 110, 120 latched in the approximated position graspingtissue therebetween, electrosurgical energy may be supplied to one orboth of sealing surfaces 112, 122 of jaw members 110, 120, respectively,of end effector assembly 100 to effect a tissue seal (see FIGS. 1A-1B).Thereafter, as mentioned above, a knife (not shown) may be advancedbetween jaw members 110, 120 to divide the previously sealed tissue.

With lever latch assembly 140 in the latched condition, as describedabove, the surgeon need not retain lever 141 in the actuated positionduring sealing and/or dividing of tissue. Such a feature helps reducessurgeon fatigue and helps ensure that a consistent and accurate closureforce between jaw members 110, 120 is applied. As can be appreciated,the length of longitudinal segments 162 of track 160 may be selected toachieve a specific closure force between jaw members 110, 120 when movedto the approximated position. As such, outer sleeve 150 may beconfigured as an interchangeable component that is releasably engageableto housing 20, allowing the user to select the desired outer sleeve 150in accordance with the desired closure force between jaw members 110,120 when in the approximated position.

The above-described lever latch assembly 140 may be selectively used bythe surgeon. For example, where it is desirable to retain jaw members110, 120 in the approximated position upon each stroke of lever 141, thesurgeon may simply translate lever 141 from the initial position to theover-actuated position, e.g., the proximal-most position, and maythereafter release lever 141 such that lever 141 is latched in theactuated position and such that jaw members 110, 120 are latched in theapproximated position. On the other hand, where repeated and/or rapidtissue sealing is desired, the surgeon may depress lever 141 to theactuated position (but not the over-actuated position) to move jawmembers 110, 120 to the approximated position. In this configuration,upon release of lever 141, since lever 141 and jaw members 110, 120 arenot latched, lever 141 and jaw members 110, 120 are returned to theinitial position and the spaced-apart position, respectively. Thisoperation may then be repeated to grasp, seal and/or divide numerousportions of tissue, without requiring lever latch assembly 140 to beunlatched after each successive operation. Further, audible and/ortactile feedback may be provided to alert the surgeon as to the positionof stop members 158 relative to track 160, e.g., to notify the surgeonas to when lever 141 has reached the actuated position and/or theover-actuated position.

Turning now to FIGS. 6A-6B, in order to unlatch lever latch assembly140, lever 141 is pulled proximally from the actuated position to theover-actuated position such that mandrel 192, drive bar 191 androtatable collar 156 are moved proximally. Likewise, stop members 158are translated proximally from valleys 171 of distal surface 168 oftrack 160 until stop members 158 contact proximal surface 165 of track160. Once again, the triangle-wave-shaped configuration of proximalsurface 165 of track 160 urges rotatable collar 156 to rotate aboutlongitudinal axis “X-X” as stop members 158 are translated from thepeaks 166 of proximal surface 165 of track 160 to the valleys 167thereof. Once lever 141 has been moved proximally back to theover-actuated position, lever 141 may be released, allowing mandrel 192,drive bar 191, and rotatable collar 156 to return distally under thebias of spring 154. As mandrel 192 and drive bar 191 are returneddistally, jaw members 110, 120 are moved back toward the spaced-apartposition. Eventually, upon further distal translation, stop members 158contact triangle-wave-shaped distal surface 168 of track 160. Thetriangle-wave-shaped configuration of distal surface 168 of track 160urges stop members 158 and, thus, collar 156 to once again rotaterelative to track 160. More specifically, triangle-wave-shaped distalsurface 168 urges stop members 158 to rotate back into alignment withlongitudinal segments 162 of track 160. Accordingly, with stop members158 aligned with longitudinal segments 162 of track 160, lever 141,mandrel 192, drive bar 191 and rotatable collar 156 are permitted totranslate further distally under the bias of spring 154 as stop members158 are translated distally through longitudinal segments 162 of track160 until lever 141 returns to the initial position. At the same time,jaw members 110, 120 are moved apart from one another, eventuallyreturning to the spaced-apart position.

With reference now to FIG. 7, a schematic illustration of track 160 isshown. Although track 160 extends annularly about outer sleeve 150, itis shown in a linear orientation for illustration purposes. As shown inFIG. 7, the triangle-wave-shaped configurations of proximal and distalsurfaces 165, 168, respectively, of track 160 are offset relative to oneanother such that, as stop members 158 are longitudinally translatedinto contact with proximal and distal surfaces 165, 168, respectively,of track 160, rotatable collar 156 is urged to rotate about longitudinalaxis “X-X,” e.g., such that stop members 158 are moved from longitudinalsegments 162 of track 160 to the annular segments 164 of track 160.Further, the number of longitudinal and annular segments 162, 164,respectively, may be varied. More specifically, track 160 may include apair of alternating longitudinal segments 162 and annular segments 164such that rotatable collar 156 is rotated through one completerevolution about longitudinal axis “X-X” upon movement of lever 141through one cycle, e.g., from the initial position to the over-actuatedposition back the actuated position and from the actuated position tothe over-actuation position back to the initial position. However, track160 may alternatively be configured to include four alternatinglongitudinal segments 162 and annular segments 164 such that rotatablecollar 156 is rotated one-half a revolution per cycle of lever 141, ortrack 160 may define various other configurations.

Referring now to FIGS. 8-11, another embodiment of a lever latchassembly configured for use with forceps 10 is shown generallyidentified by reference numeral 240. Lever latch assembly 240, similarto lever latch assembly 140 (FIGS. 2A-7) includes a lever 241 that ispivotably coupled to housing 20 of forceps 10 via pivot pin 245 and isconfigured to move between an initial position and an actuated positionfor translating drive bar 291 between a distal position and a proximalposition to move jaw members 110, 120 (FIGS. 1A-1B) between thespaced-apart position (FIG. 1A) and the approximated position (FIG. 1B).

Similar to the previous embodiment, lever 241 includes a pair of flanges243 extending upwardly on either side of drive bar 291. Lever latchassembly 240 further includes a cartridge 250 having first and secondsleeves 252, 260, respectively, extending longitudinally therethrough ingenerally parallel orientation relative to one another. First sleeve 252is centered about longitudinal axis “X-X” (see FIGS. 1A and 1B) and isconfigured for fixedly receiving drive bar 291 therethrough. Morespecifically, cartridge 250 is interdisposed between drive bar 291 andflanges 243 of lever 241 and includes proximal and distal shoulders 253,255, respectively, configured to retain flanges 243 of lever 241therebetween. Accordingly, when lever 241 is moved from the initialposition to the actuated position, flanges 243 contact proximal shoulder253 of cartridge 250 and urge drive bar 291 proximally to move jawmembers 110, 120 toward the approximated position (FIG. 1B). On theother hand, when lever 241 is returned from the actuated position backto the initial position, flanges 243 contact distal shoulder 255 ofcartridge 250 and urge drive bar 291 distally to move jaw members 110,120 back toward the spaced-apart position (FIG. 1A). Further, a spring254 (or other biasing member) may be disposed within cartridge 250 tobias cartridge 250 and drive bar 291 distally. As such, with flanges 243of lever 241 engaged between shoulders 253, 255 of cartridge 250, spring254 also biases lever 241 toward the initial position and jaw members110, 120 toward the spaced-apart position (FIG. 1A).

With continued reference to FIGS. 8-11, second sleeve 260 of cartridge250 is configured to slidably receive free end 263 of post 262therethrough. Post 262 is rotatably coupled to housing 20 of forceps 10at a fixed end 264 thereof and extends proximally therefrom to free end263. Further, post 262 includes a track 270 defined therein, extendingannularly therearound, and disposed toward free end 263 thereof. A pairof opposed stop members 278 disposed on cartridge 250 and extendingradially inwardly into second sleeve 260 are engaged within track 270 ofpost 262. More specifically, as described above with respect to leverlatch assembly 140, stop members 278 of cartridge 250 are configured totranslate along track 270 upon translation of cartridge 250 relative topost 262, e.g., upon movement of lever 241 from the initial position tothe actuated position. Track 270 is configured substantially similarlyto track 160 (FIG. 7) and stop members 278 are configured to translateand rotate relative to track 270 to latch and unlatch lever latchassembly 240 in a similar fashion as described above with respect tolever latch assembly 140 (see FIGS. 2A-7). In particular, as will bedescribed in greater detail below, as stop members 278 of cartridge 250are translated along track 270, post 262 is urged to rotate relative tocartridge 250 and, thus, stop members 278 such that lever 241 may belatched in the actuated position, thereby latching jaw members 110, 120in the approximated position (FIG. 1B). Thus, different from lever latchassembly 140 (FIGS. 2A-7), stop members 278 are fixed relative tohousing 20 of forceps 10, while track 270 is translatable and rotatablerelative to stop members 278 upon latching and unlatching of lever latchassembly 240. Lever latch assembly 240 may otherwise include any of thefeatures of lever latch assembly 140, discussed above, and vice versa.

Continuing with reference to FIGS. 8-11, the use and operation of leverlatch assembly 240 will be described. Initially, as shown in FIG. 8,lever 241 is disposed in the initial position, cartridge 250 and drivebar 291 are disposed in the distal position and jaw members 110, 120 aredisposed in the spaced-apart position (FIG. 1A). Further, in thisposition, stop members 278 are disposed at the distal ends 273 oflongitudinal segments 272 of track 270 of post 262.

Turning now to FIG. 9, when it is desired to move jaw members 110, 120to the approximated position, e.g., to grasp tissue between sealingsurfaces 112, 122 of jaw members 110, 120, respectively, (see FIGS.1A-1B) lever 241 is moved proximally from the initial position towardthe actuated position. As mentioned above, moving lever 241 from theinitial position toward the actuated position translates cartridge 250and, thus, drive bar 291 proximally to pivot jaw member 110 about pivotpin 103 toward jaw member 120 (see FIG. 1B). At the same time, cartridge250 is translated proximally relative to post 262 such that stop members278 are translated proximally along longitudinal segments 272 of track270. Lever 241 is moved further proximally past the actuated positionuntil stop members 278 have translated proximally completely throughlongitudinal segments 272 of track 270 and into abutment with proximalsurface 275 of track 270 (the over-actuated position). As stop members278 contact the triangle-wave-shaped proximal surface 275 of track 270,post 262 is urged to rotate relative to stop members 278 such that stopmembers 278 are translated along track 270 of post 262 from the peaks276 of proximal surface 275 of track 270 to the valleys 277 thereof. Inthis position, due to the rotation of post 262 relative to stop members278, stop members 278 are no longer aligned with longitudinal segments272 of track 270.

Once this over-actuated position has been achieved, lever 241 may bereleased, allowing lever 241 to return distally toward the actuatedposition under the bias of spring 254. As lever 241 is translateddistally, stop members 278 are likewise translated distally relative totrack 270 of post 262, eventually contacting distal surface 281 of track270, which inhibits further distal translation of lever 241. Once again,due to the triangle-wave-shaped configuration of distal surface 281 oftrack 270, stop members 278 are urged from the peaks 283 of distalsurface 281 of track 270 to the valleys 285 thereof, urging post 262 torotate relative to stop members 278. Stop members 278 are retained inthe valleys 285 of distal surface 281 of track 270 under the bias ofspring 254 such that lever 241 is latched in the actuated position andsuch that cartridge 250 and drive bar 291 are inhibited from returningdistally. Accordingly, with stop members 278 retained within valleys 285of distal surface 281 of track 270, jaw members 110, 120 are latched inthe approximated position (see FIG. 18). As discussed above, with jawmembers 110, 120 latched in the approximated position grasping tissuetherebetween, forceps 10 may be used to seal and/or divide tissuegrasped between jaw members 110, 120 (see FIG. 1B).

Turning now to FIG. 11, in order to unlatch lever latch assembly 240,lever 241 is pulled proximally from the actuated position to theover-actuated position such that stop members 278 are translatedproximally from valleys 285 of distal surface 281 of track 270 intocontact with proximal surface 275 of track 270. Upon contacting proximalsurface 275 of track 270, the triangle-wave-shaped proximal surface 275of track 270 urges post 262 to rotate relative to stop members 278 suchthat stop members 278 are moved along track 270 from the peaks 276 ofproximal surface 275 of track 270 to the valleys 277 thereof. Thisrotation of post 262 relative to stop members 278 aligns stop members278 with distally-sloping portions of the triangle-wave-shaped distalsurface 281 of track 270. The distally-sloping portions of distalsurface 281 of track 270 feed into longitudinal segments 272 of track270. As such, upon release of lever 241 from the over-actuated position,stop members 278 are translated proximally into contact with distalsurface 281 of track 270, rotating post 262 relative to stop members278. Eventually, post 262 is rotated sufficiently such that stop members278 are once again aligned with longitudinal segments 272 of track 270.Once this alignment is achieved, cartridge 250 and drive bar 291 arepermitted to translate distally under the bias of spring 254 as stopmembers 278 are translated distally through longitudinal segments 272 oftrack 270. At the same time, lever 241 is returned to the initialposition and jaw members 110, 120 are returned to the spaced-apartposition.

Turning now to FIGS. 12-15, yet another embodiment of a lever latchassembly configured for use with forceps 10 is shown. Similar to leverlatch assembly 140, lever latch assembly 340 includes a lever 341 thatis pivotably coupled to housing 20 and extends downwardly therefrom.Lever 341 includes a pair of flanges 343 that extend upwardly on eitherside of drive bar 391, ultimately engaging pivot pin 345 on either endthereof. Lever 341 is pivotable about pivot pin 345 relative to housing20 between an initial position and an actuated position. Similarly asdiscussed above, flanges 343 of lever 341 are coupled to drive bar 391via a mandrel 392 such that moving lever 341 from the initial positionto the actuated position translates drive bar 391 proximally to move jawmembers 110, 120 toward the approximated position. On the other hand,moving lever 341 from the actuated position back to the initial positiontranslates drive bar 391 distally to move jaw members 110, 120 backtoward the spaced-apart position.

Housing 20 further includes a cartridge 350 disposed therein andconfigured for longitudinal translation along longitudinal axis “X-X.”Cartridge 350 is configured to retain drive bar 391 and mandrel 392therein. Further, a biasing member, e.g., spring 354, may be disposedbetween proximal wall 352 of cartridge 350 and mandrel 392 to bias drivebar 391 toward a distal position, e.g., to bias jaw members 110, 120toward a spaced-apart position. Thus, when lever 341 is released,cartridge 350, mandrel 392 and drive bar 391 are translated distallyalong longitudinal axis “X-X,” under the bias of spring 354, to returnjaw members 110, 120 to the spaced-apart position.

With continued reference to FIGS. 12-15, lever latch mechanism 340further includes a post 360 pivotably coupled to housing 20 at proximalend 362 thereof. Post 360 includes a proximal shoulder 364 disposed atproximal end 362 thereof and a distal snap feature 366 disposed at adistal end 365 thereof. As best shown in FIG. 15, a biasing member,e.g., a spring 367, is positionable about post 360 adjacent proximalshoulder 364. A sleeve 370 having a track 372 defined therein on anouter periphery thereof is slidably and rotatably positionable aboutpost 360. More particularly, sleeve 370 is configured to slide overdistal end 365 of post 360 such that sleeve 370 is snap-fittinglyretained thereon. In other words, once sleeve is slid over post 360,snap-fit feature 366 inhibits sleeve 370 from being removed from post360. Other mechanisms (not shown) that are configured to retain sleeve370 on post 360 while allowing sleeve 370 to translate and rotaterelative to post 360 may also be provided. As assembled, as shown inFIGS. 12 and 13, spring 367 is interdisposed between proximal shoulder364 of post 360 and sleeve 370, biasing sleeve 370 toward distal end 365of post 360.

As mentioned above, sleeve 370 includes a track 372 defined therein.Track 372 is similar to track 160 defined within sleeve 150 of leverlatch assembly 140 (see FIGS. 2A-7) and extends annularly about sleeve370. More specifically, track 372 includes one or more longitudinalsegments 373 and one or more annular segments 375. The proximal anddistal surfaces 377, 379, respectively, of annular segments 375 of track372 define triangle-wave-shaped configurations that are offset relativeto one another.

As best shown in FIG. 15, lever 341 includes a pair of opposed stopmembers 378 extending inwardly from flanges 343. Stop members 378 areconfigured to engage track 372 of sleeve 370 and to translate alongtrack 372 of sleeve 370. Due to the triangle-wave-shaped configurationof track 372, stop members 378 also urge sleeve 370 to rotate about post360 upon translation of stop members 378 along track 372, as will bedescribed in greater detail below.

Turning now to FIGS. 12-13, in conjunction with FIG. 14, the use andoperation of lever latch assembly 340 will be described. Initially, asshown in FIG. 12, lever 341 is disposed in the initial position, jawmembers 110, 120 are disposed in the spaced-apart position, and stopmembers 378 of lever 341 are disposed at distal ends 374 of longitudinalsegments 373 of track 372 of sleeve 370. In this initial position, post360 is angled upwardly off of post axis “P-P” toward drive bar 391 andsleeve 370 is biased toward distal end 365 of post 360 by spring 367.

In order to move jaw members 110, 120 to the approximated position,e.g., to grasp tissue therebetween, lever 341 is pulled proximally fromthe initial position toward the actuated position. As lever 341 ispulled proximally, cartridge 350 and drive bar 391 are likewisetranslated proximally against the bias of spring 354 to pivot jawmembers 110, 120 relative to one another from the spaced-apart positiontoward the approximated position. At the same time, stop members 378 oflever 341 are translated proximally along longitudinal segments 373 oftrack 372 of sleeve 370. Further, as stop members 378 are translatedalong track 372 of sleeve 370, i.e., as lever 373 is translatedproximally, post 360 is pivoted downwardly about proximal end 362thereof toward post axis “P-P.”

As in the previous embodiments, lever 341 is moved further proximallyuntil stop members 378 have translated proximally completely throughlongitudinal segments 373 of track 372 and into abutment with proximalsurface 377 of track 372. This position corresponds to the over-actuatedposition of lever 341. Upon contact of stop members 378 with theproximal surface 377 of track 372, stop members 378 are urged againstthe triangle-wave-shaped proximal surface 377 of track 372, causingsleeve 370 to rotate about post 360, moving stop members 378 along track372 from the peaks 381 of proximal surface 377 of track 372 to thevalleys 383 thereof (see FIG. 14).

Once lever 341 has been moved to the over-actuated position, lever 341may be released such that lever 341 and stop members 378 are translateddistally relative to track 372 under the bias of spring 367. Eventually,stop members 378 are translated distally into engagement with distalsurface 379 of track 372 under the bias of spring 367, while cartridge350 and drive bar 391 are returned distally under the bias of spring354. However, upon engagement between stop members 378 and distalsurface 379 of track 372, further distal translation of stop members378, lever 341, cartridge 350 and drive bar 391 is inhibited. Morespecifically, as stop members 378 are translated distally intoengagement with distal surface 379 of track 372, stop members 378 urgesleeve 370 to rotate about post 360 such that stop members 378 aretranslated from the peaks 385 of distal surface 379 to the valleys 387thereof (see FIG. 14). Spring 367 biases stop members 378 into valleys387 of distal surface 379 of track 372, inhibiting further distaltranslation of lever 341, mandrel 392 and drive bar 391. This position,as shown in FIG. 13, corresponds to the latched condition of lever latchassembly 340, wherein lever 341 is latched in the actuated position andwherein jaw members 110, 120 are latched in the approximated position.

Similarly as described above with reference to lever latch assemblies140 and 240 (see FIGS. 2A-7 and 8-11, respectively), to unlatch leverlatch assembly 340, lever 341 is pulled proximally from the actuatedposition to the over-actuated position to translate stop members 378proximally into engagement with proximal surface 377 of track 372. Uponcontact with the triangle-wave-shaped proximal surface 377 of track 372,stop members 378 urge sleeve 370 to rotate about post 360 such that stopmembers 378 are moved to the valleys 383 of proximal surface 377 oftrack 372.

Thereafter, lever 341 may be released, allowing lever 341, cartridge 350and drive bar 391 to return distally, thus allowing jaw members 110, 120to move back toward the spaced-apart position. At the same time, stopmembers 378 are translated distally along track 372, eventuallycontacting distal surface 379 of track 372 and urging sleeve 370 torotate about post 360 until stop members 378 are once again aligned withlongitudinal segments 373 of track 372. Once this position is achieved,lever 341 is permitted to translate distally back to the initialposition as stop members 378 are translated distally throughlongitudinal segments 373 of track 372 to distal ends 374 thereof.Likewise, cartridge 350 and drive bar 391 are return distally under thebias of spring 354, urging jaw members 110, 120 to pivot relative to oneanother back to the spaced-apart position.

With reference now to FIGS. 16-17, yet another embodiment of a leverlatch assembly is shown. Lever latch assembly 440 is substantiallysimilar to lever latch assembly 340 (FIGS. 12-15) and includes a post460 pivotably coupled to housing 20 at proximal end 462 thereof. Post460 further includes a proximal shoulder 464 disposed at proximal end462 thereof and an interference member 466 disposed at a distal end 468thereof. A spring 472 is positionable about post 460 adjacent proximalshoulder 464. A sleeve 470 including a track 474 defined therein on anouter periphery thereof is slidably and rotatably positionable aboutpost 460 such that spring 472 is interdisposed between proximal shoulder464 of post 460 and sleeve 470. Sleeve 470 is substantially similar tosleeve 370 of lever latch assembly 340 (see FIGS. 12-15) and includes atrack 474 having one or more longitudinal segments 475 and one or moreannular segments 477 extending annularly about sleeve 470 in alternatingrelation relative to one another. As described above in previousembodiments, stop members 478 of lever 441 are engaged within track 474of sleeve 470 and are translatable therealong. Track 474 of sleeve 470is substantially similar to the tracks of lever latch assemblies 140,240, 340, described above.

Initially, as shown in FIG. 16, lever 441 is disposed in the initialposition, jaw members 110, 120 are disposed in the spaced-apartposition, and stop members 478 of lever 441 are disposed at distal ends479 of longitudinal segments 475 of track 474 of sleeve 470. Further, inthis initial position, post 460 is angled downwardly relative to postaxis “P-P.”

In order to move jaw members 110, 120 to the approximated position,lever 441 is pulled proximally from the initial position toward theactuated position, translating cartridge 450 and drive bar 491proximally against the bias of spring 452 and pivoting jaw members 110,120 toward the approximated position. At the same time, stop members 478of lever 441 are translated proximally along longitudinal segments 475of track 474 of sleeve 470. As stop members 478 are translated alonglongitudinal segments 475 of track 472 of sleeve 470, post 460 ispivoted upwardly into alignment with post axis “P-P.” In this position,interference member 466, which is disposed at distal end 468 of post460, is moved into position adjacent a distal end 454 of cartridge 450.More particularly, in this position, interference member 466 is disposedbetween housing 20 and cartridge 450 to inhibit distal translation ofcartridge 450 along longitudinal axis “X-X.”

As in the previous embodiments, lever 441 is moved proximally until stopmembers 478 have been translated proximally completely throughlongitudinal segments 475 of track 474 and into abutment withtriangle-wave-shaped proximal surface 483 of track 474 to rotate sleeve470 about post 460, as discussed above. Thereafter, upon release oflever 441, stop members 478 are translated distally relative to track474 into engagement with distal surface 481 of track 474. With stopmembers 478 engaged within distal surface 481 of track 474 of sleeve470, post 460 is retained in position relative to post axis “P-P,” e.g.,in alignment with post axis “P-P.” As mentioned above, in this position,interference member 466 is disposed between housing 20 and cartridge450, inhibiting cartridge 450 and, thus, drive bar 491 from returningdistally, thereby latching jaw members 110, 120 in the approximatedposition. As can be appreciated, when jaw members 110, 120 are latchedin the approximated position, lever 441 is latched in the actuatedposition.

In order to unlatch lever latch assembly 440, lever 441 is pulledproximally from the actuated position to the over-actuated position suchthat stop members 478 are translated proximally from distal surface 481of track 474, into engagement with proximal surface 483 of track 474.The triangle-wave-shaped configuration of proximal surface 483 of track474 urges sleeve 470 to rotate about post 460 upon contact with stopmembers 478 such that stop members 478 are moved into alignment withlongitudinal segments 475 of track 474. With stop members 478 alignedwith longitudinal segments 475 of track 474, lever 441 is permitted,upon release thereof, to translate from the actuated position back tothe initial position as stop members 478 are translated distally throughlongitudinal segments 475 of track 474. At the same time, post 460 ispivoted about proximal end 462 thereof downwardly relative to post axis“P-P,” disengaging interference member 466 from between cartridge 450and housing 20. With interference member 466 no longer inhibitingcartridge 450 and drive bar 491 from returning distally, spring 452urges cartridge 450 and drive bar 491 distally such that jaw members110, 120 are returned to the spaced-apart position.

With reference now to FIGS. 18-20B, still another embodiment of a leverlatch assembly is shown configured for use with forceps 10. Lever latchassembly 540 includes a lever 541 having a pair of flanges 543 disposedon either side of drive bar 591 and between proximal and distal rims593, 594, respectively, of mandrel 592, such that moving lever 541between the initial position and the actuated position translates drivebar 591 longitudinally along longitudinal axis “X-X” to move jaw members110, 120 between the spaced-apart position and the approximatedposition. Further, mandrel 592 and drive bar 591 are disposed within acartridge 550. Cartridge 550 is disposed within housing 20 and ispositioned about longitudinal axis “X-X.” Cartridge 550 is configured toretain drive bar 591 and mandrel 592 therein and includes a spring 552disposed between proximal wall 554 of cartridge 550 and proximal rim 593of mandrel 592 to bias drive bar 591 distally, e.g., to bias jaw members110, 120 toward the spaced-apart position.

Continuing with reference to FIGS. 18-20A, lever latch mechanism 540further includes a post 560 pivotably coupled to housing 20 at proximalend 563 thereof. Post 560 includes a proximal shoulder 562 disposed atproximal end 563 thereof and a distal snap feature 566 disposed at adistal end 565 thereof. A sleeve 570 including a track 572 defined on anouter periphery thereof and an annular recess 580 defined therein isslidably and rotatably positionable about post 560. An “L”-shaped spring576 is disposed about and engaged to post 560 at proximal end 563thereof and extends distally therefrom. “L”-shaped spring 576 includes astop member 578 disposed at the free end thereof that extends downwardlyinto engagement with track 572 of sleeve 570.

Track 572 of sleeve 570 is similar to track 572 defined within sleeve570 of lever latch assembly 140 (see FIGS. 2A-7), except thatlongitudinal segments 573 of track 572 extend proximally along sleeve570 from annular segments 574 of track 572. As mentioned above, stopmember 578 of “L”-shaped spring 576 is engaged within track 572 and istranslatable along track 572. Lever 541, on the other hand, includes apair of protrusions 542 extending inwardly from flanges 543. Protrusions542 of lever 541 are engaged within annular recess 580 of sleeve 570such that, as lever 541 is moved between the initial position and theactuated position, sleeve 570 is translated along post 560. At the sametime, post 560 is pivoted relative to post axis “P-P” about proximal end563 of post 560 as lever 541 is moved between the initial position andthe actuated position. As will be described in greater detail below, aslever 451 is moved between the initial position and the actuatedposition to pivot post 560 and translate sleeve 570 along post 560, stopmember 578 of “L”-shaped spring 576 is translated along track 572defined within sleeve 570 to latch and unlatch lever latch assembly 540.

With continued reference to FIGS. 18-20A, the use and operation of leverlatch assembly 540 will be described. Initially, as shown in FIG. 18,lever 541 is disposed in the initial position, jaw members 110, 120 aredisposed in the spaced-apart position, stop member 578 of “L”-shapedspring 576 is disposed at proximal end 575 of longitudinal segment 573of track 572, and protrusions 542 of lever 541 retain sleeve 570 towarda distal end 565 of post 560. Further, in this initial position, post560 is angled upwardly relative to post axis “P-P” toward drive bar 591,as shown in FIG. 18.

In order to move jaw members 110, 120 to the approximated position, asin the previous embodiments, lever 541 is pulled proximally from theinitial position toward the actuated position, translating cartridge 550and drive bar 591 proximally against the bias of spring 552 to pivot jawmembers 110, 120 toward the approximated position. At the same time,protrusions 542 of lever 541 urge sleeve 570 proximally along post 560and effect pivoting of post 560 downwardly toward post axis “P-P.”Further, upon movement of lever 541 toward the actuated position, stopmember 578 of “L”-shaped spring 576 is moved distally relative to sleeve570 along longitudinal segment 573 of track 572.

Lever 541 is moved further proximally to the over-actuated position totranslate sleeve 570 further distally relative to post 560 such thatstop member 578 of “L”-shaped spring 576 is translated completelythrough longitudinal segment 573 of track 572 and into engagement withdistal surface 583 of track 572. As stop member 578 is urged against thetriangle-wave-shaped distal surface 583 of track 572, sleeve 570 isrotated above post 560 and relative to “L”-shaped spring 576 to engagestop member 578 within distal surface 583 of track 572.

Thereafter, upon release of lever 541, stop member 578 is translatedproximally relative to track 572, under the bias of “L”-shaped spring576, into engagement with proximal surface 581 of track 572. Stop member578 is retained in engagement with the triangle-wave-shaped proximalsurface 581 of track 572 under the bias of “L”-shaped spring 576,inhibiting lever 541, sleeve 570, cartridge 550 and drive bar 591 fromreturning distally. This latched condition, as shown in FIG. 19,corresponds to the actuated position of lever 541 and, thus, theapproximated position of jaw members 110, 120. In the actuated position,as shown in FIG. 19, post 560 is substantially aligned with post axis“P-P.”

Lever latch assembly 540 is unlatched similarly to lever latchassemblies 140, 240, 340, and 440, discussed above. More specifically,to unlatch lever latch assembly 540, lever 541 is pulled proximally fromthe actuated position to the over-actuated position such thatprotrusions 542 of lever 541 urge sleeve 570 proximally along post 560.As a result, sleeve 570 is moved distally relative to stop member 578such that stop member 578 is translated from proximal surface 581 oftrack 572 into engagement with distal surface 583 of track 572. Thetriangle-wave-shaped configuration of distal surface 583 of track 572urges sleeve 570 to rotate about post 560 upon contact with stop member578.

Thereafter, upon release of lever 541, cartridge 550 and drive bar 591are returned distally under the bias of spring 552 such that jaw members110, 120 are moved back toward the spaced-apart position. At the sametime, lever 541 is returned distally, thereby translating sleeve 570distally along post 560, causing post 560 to pivot upwardly relative topost axis “P-P” toward drive bar 591. Further, due to the distaltranslation of sleeve 570 relative to “L”-shaped spring 576, stop member578 is translated along track 572 into engagement withtriangle-wave-shaped distal surface 583 of track 572. More particularly,stop member 578 is urged into engagement with distal surface 583 ofsleeve 570 such that sleeve 570 is rotated about post 560 until stopmember 578 is moved into alignment with longitudinal segment 573 oftrack 572. With stop member 578 aligned with longitudinal segment 573 oftrack 572, lever 541 is permitted to translate distally back to theinitial position as stop member 578 is translated proximally throughlongitudinal segment 573 of track 572. At the same time, sleeve 570,cartridge 550 and drive bar 591 are returned distally and jaw members110, 120 are returned to the spaced-apart position.

Turning now to FIGS. 20A and 2013, post 560 is shown including sleeve570 disposed thereabout. As discussed in detail above, track 572 definedwithin sleeve 570 includes one or more annular triangle-wave-shapedsegments 574 and one or more longitudinal segments 573 extendingproximally from annular segment(s) 574. Track 572 may further include acontoured floor 585 correspondingly configured relative to the annularand longitudinal segments 574, 573, respectively, of track 572. Morespecifically stop member 578 of “L”-shaped spring 576 (FIGS. 18-19) maybe configured to not only translate longitudinally and rotationallyrelative to track 572, but may further be configured to translateradially, e.g., inwardly and outwardly, with respect to track 572, as afunction of the contoured floor 585 of track 572. Such a featureprovides for three-dimensional translation of stop member 578 (FIGS.18-19) along track 572 to increase the engagement and positioning ofstop member 578 (FIGS. 18-19) relative to sleeve 570. For example, asstop member 578 (FIGS. 18-19) is translated distally along longitudinalsegment 573 of track 572, stop member 578 (FIGS. 18-19) may likewise betranslated along an upwardly-angled portion 586 of contoured floor 585of track 572. Stop member 578 (FIGS. 18-19) may then drop-off into alower-disposed portion 588 of floor 585 upon positioning within annularsegment 574 of track 572. As can be appreciated, and as shown in FIG.206, floor 585 of track 572 may define a plurality of other varyingdepth and/or angled portions such that stop member 578 (FIGS. 18-19) maybe translated through these various portions of floor 585 as stop member578 (FIGS. 18-19) is translated from longitudinal segment 573, proximaland distal surfaces 581, 583, respectively, of annular segment 574, andback to longitudinal segment 573 of track 572. Other configurations oftrack 572 may also be provided. Additionally, any of the tracks of leverlatch assemblies 140, 240, 340, 440 discussed above may includesimilarly-configured contoured floors to define a three-dimensionalconfiguration.

From the foregoing and with reference to the various figure drawings,those skilled in the art will appreciate that certain modifications canalso be made to the present disclosure without departing from the scopeof the same. While several embodiments of the disclosure have been shownin the drawings, it is not intended that the disclosure be limitedthereto, as it is intended that the disclosure be as broad in scope asthe art will allow and that the specification be read likewise.Therefore, the above description should not be construed as limiting,but merely as exemplifications of particular embodiments. Those skilledin the art will envision other modifications within the scope and spiritof the claims appended hereto.

1. A surgical instrument, comprising: an end effector assembly includinga pair of jaw members pivotably coupled to one another, at least one ofthe jaw members moveable relative to the other between a spaced-apartposition and an approximated position for grasping tissue therebetween;a drive bar defining a longitudinal axis, the drive bar longitudinallytranslatable between a distal position and a proximal position formoving the jaw members between the spaced-apart position and theapproximated position; and a latch mechanism including: a lever moveablebetween an initial position and an actuated position for translating thedrive bar between the distal position and the proximal position; asleeve co-axially disposed about the drive bar, the sleeve including atrack extending annularly therearound, the track having at least onesubstantially radial segment and at least one substantially longitudinalsegment; and a rotatable collar interdisposed between the sleeve and thedrive bar, the rotatable collar including at least one stop memberextending radially outwardly from an outer periphery thereof, the atleast one stop member engaged within the track and configured totranslate along the track from a first position corresponding to theinitial position of the lever, wherein the at least one stop member ispositioned within one of the at least one substantially longitudinalsegments, to a second position corresponding to the actuated position ofthe lever, wherein the at least one stop member is engaged within one ofthe at least one substantially radial segments to lock the lever in theactuated position.
 2. The surgical instrument according to claim 1,wherein the at least one stop member is configured to translate from thefirst position to a third position, corresponding to an over-actuatedposition of the lever, and back to the second position to lock the leverin the actuated position.
 3. The surgical instrument according to claim1, wherein the at least one stop member is configured to translate fromthe second position to a third position, corresponding to anover-actuated position of the lever, such that the at least one stopmember is translated along the track from the at least one substantiallyradial segment to one of the at least one substantially longitudinalsegments to permit the lever to return to the initial position.
 4. Thesurgical instrument according to claim 1, wherein the track includes aplurality of alternating substantially longitudinal segments andsubstantially radial segments, the substantially longitudinal segmentsextending distally along the sleeve relative to the substantially radialsegments.
 5. The surgical instrument according to claim 1, furthercomprising a biasing member annularly disposed between the drive bar andthe sleeve, the biasing member configured to bias the rotatable collardistally relative to the sleeve.
 6. A surgical instrument, comprising:an end effector assembly including a pair of jaw members pivotablycoupled to one another, at least one of the jaw members moveablerelative to the other between a spaced-apart position and anapproximated position for grasping tissue therebetween; a drive bardefining a longitudinal axis, the drive bar longitudinally translatablebetween a distal position and a proximal position for moving the jawmembers between the spaced-apart position and the approximated position;and a latch mechanism including: a lever moveable between an initialposition and an actuated position for translating the drive bar betweenthe distal position and the proximal position; a cartridge includingfirst and second lumens defined therein and extending longitudinallytherethrough in substantially parallel orientation relative to oneanother, the first lumen configured to slidably receive a portion of thedrive bar therethrough; a rotatable post including a fixed end and afree end, the rotatable post slidably disposed within the second lumenof the cartridge and including a track extending annularly therearoundtoward the free end thereof, the track having at least one substantiallyradial segment and at least one substantially longitudinal segment; andat least one stop member fixedly coupled to the cartridge and extendingradially inwardly into the second lumen of the cartridge, the at leastone stop member engaged within the track and configured to translatealong the track from a first position, corresponding to the initialposition of the lever, wherein the at least one stop member ispositioned within one of the at least one substantially longitudinalsegments, to a second position, corresponding to the actuated positionof the lever, wherein the at least one stop member is engaged within oneof the at least one substantially radial segments to lock the lever inthe actuated position.
 7. The surgical instrument according to claim 6,wherein the at least one stop member is configured to translate from thefirst position to a third position, corresponding to an over-actuatedposition of the lever, and back to the second position to lock the leverin the actuated position.
 8. The surgical instrument according to claim6, wherein the at least one stop member is configured to translate fromthe second position to a third position, corresponding to anover-actuated position of the lever, such that the at least one stopmember is translated along the track from the at least one substantiallyradial segment to one of the at least one substantially longitudinalsegments to permit the lever to return to the initial position.
 9. Thesurgical instrument according to claim 6, further comprising a biasingmember annularly disposed between the drive bar and the cartridge andconfigured to bias the cartridge distally relative to the rotatablepost.
 10. A surgical instrument, comprising: an end effector assemblyincluding a pair of jaw members pivotably coupled to one another, atleast one of the jaw members moveable relative to the other between aspaced-apart position and an approximated position for grasping tissuetherebetween; a drive bar defining a longitudinal axis, the drive barlongitudinally translatable between a distal position and a proximalposition for moving the jaw members between the spaced-apart positionand the approximated position; and a latch mechanism including: a posthaving a fixed end and a free end, the post pivotable about the fixedend thereof; a sleeve rotatably and slidably disposed about the post,the sleeve including a track extending annularly therearound, the trackhaving at least one substantially radial segment and at least onesubstantially longitudinal segment; a lever moveable between an initialposition and an actuated position for translating the drive bar betweenthe distal position and the proximal position; and at least one stopmember engaged within the track and configured to translate along thetrack from a first position, corresponding to the initial position ofthe lever, wherein the at least one stop member is positioned within oneof the at least one substantially longitudinal segments, to a secondposition, corresponding to the actuated position of the lever, whereinthe at least one stop member is engaged within one of the at least onesubstantially radial segments to lock the lever in the actuatedposition.
 11. The surgical instrument according to claim 10, wherein theat least one stop member is configured to translate from the firstposition to a third position, corresponding to an over-actuated positionof the lever, and back to the second position to lock the lever in theactuated position.
 12. The surgical instrument according to claim 10,wherein the at least one stop member is configured to translate from thesecond position to a third position, corresponding to an over-actuatedposition of the lever, such that the at least one stop member istranslated along the track from the at least one substantially radialsegment to one of the at least one substantially longitudinal segmentsto permit the lever to return to the initial position.
 13. The surgicalinstrument according to claim 10, wherein the lever includes a pair offlanges disposed on either side of the sleeve, each flange including oneof the stop members extending inwardly therefrom such that movement ofthe lever effects corresponding movement of the at least one stop memberalong the track.
 14. The surgical instrument according to claim 10,further comprising a biasing member disposed between the sleeve and thefree end of the post, the biasing member configured to bias the sleevedistally relative to the post.
 15. The surgical instrument according toclaim 10, further comprising an interference member disposed at the freeend of the post and configured such that, upon movement of the lever tothe actuated position, the interference member is pivoted intoengagement with the drive bar to inhibit the drive bar from returningdistally.
 16. The surgical instrument according to claim 10, furthercomprising an “L”-spring, the “L”-spring including a first end rotatablycoupled to the post toward the fixed end thereof and a second end havingthe stop member extending therefrom.
 17. The surgical instrumentaccording to claim 10, wherein the lever includes a pair of flangesdisposed on either side of the post, the flanges coupled between thesleeve and the free end of the post such that movement of the levereffects corresponding movement of the sleeve relative to the stopmember, thereby moving the stop member along the track.
 18. The surgicalinstrument according to claim 10, wherein the track includes a pluralityof alternating substantially longitudinal segments and substantiallyradial segments.
 19. The surgical instrument according to claim 10,wherein the track includes a contoured floor such that the at least onestop member is translated three-dimensionally along the track betweenthe substantially longitudinal segments and the substantially radialsegments thereof.